Select saute setting on a 6-qt. electric pressure cooker. Adjust for medium heat; add oil. When oil is hot, cook and stir cumin seeds until fragrant and they start to pop. Add onion; cook until crisp-tender, about 2 minutes. Add tomatoes and ginger; cook 1 minute. Add chili powder, garam masala, cumin, salt and turmeric; cook until fragrant, about 1 minute. Stir in cauliflower, potatoes and water. Press cancel., Lock lid; close pressure-release valve. Adjust to pressure-cook on high for 3 minutes. Let pressure release naturally for 5 minutes; quick-release any remaining pressure. Sprinkle with cilantro if desired.